87013-18-1Relevant academic research and scientific papers
Discotic liquid crystalline poly(propylene imine) dendrimers based on triphenylene
McKenna, Mark D.,Barbera, Joaquin,Marcos, Mercedes,Serrano, Jose Luis
, p. 619 - 625 (2005)
The design, synthesis, and mesomorphic properties of a new series of homodendrimers consisting of the commercially available poly(propylene imine) (PPI) dendrimers (G = 1-5), PPI-(NH2)n (n = 4, 8, 16, 32, 64), functionalized with a discotic triphenylene moiety are reported. The liquid crystalline behavior was investigated by means of differential scanning calorimetry (DSC), polarizing-light optical microscopy (POM), and X-ray diffractometry (XRD). All of the homodendrimers showed mesomorphic properties, with the second to fifth generations giving a hexagonal columnar mesophase (Colh) and the first generation a rectangular columnar mesophase (Colr). The X-ray study reveals that these mesophases show a highly ordered structure with segregation of triphenylenes and dendrimers into separate columns and a regular stacking distance inside the triphenylene columns. GPC analysis showed that the dendrimers had good monodispersity and MALDI-TOF studies of the first three generations gave good evidence that all of the terminal amino groups of the dendrimers were functionalized with a discotic unit.
Ring-Closure Reactions. 21. Intramolecular β-Elimination Competing with Ring Formation from o-(ω-Bromoalkoxy)phenoxides over a Wide Range of Ring Sizes
Cort, Antonella Dalla,Mandolini, Luigi,Masci, Bernardo
, p. 3979 - 3982 (2007/10/02)
Unimolecular β-elimination of HBr from the CH2CH2Br end of o--OC6H4O(CH2)n-4Br has been interpreted as an E2-type reaction promoted by the distal phenoxide group acting as a base.Combination of careful product analyses with kinetic data has provided rate constants and effective molarities for intramolecularly assisted elimination reactions occurring through 7-, 8-, 9-, 10-, and 14-membered ring transition states.A comparison is carried out with the competing intramolecular substitution reactions leading to ring formation.Attention is called to the specific entropic and geometrical requirements of intramolecular elimination in which the donor-proton-acceptor arrangement is a part of a cyclic structure.The importance of the present results in the general field of intramolecular acid or base catalysis phenomena is discussed.
